Packaged semiconductor dies, including memory chips, microprocessor chips, and imager chips, typically include one or more semiconductor dies mounted on a package substrate and encased in a plastic protective covering. Each semiconductor die includes an integrated circuit and bond pads electrically connecting the integrated circuit to a plurality of wirebonds. The wirebonds are coupled to the package substrate, and the package substrate, in turn, electrically routes signals between the die and a printed circuit board connected to off-chip electrical devices.
Some die packages have through-silicon vias (TSVs) in lieu of wirebonds. A TSV extends through the substrate of the die and electrically connects the die to the package substrate. A TSV can reduce the package footprint and improve electrical performance. However, one challenge with TSVs is that they reduce circuit density within the die because they take up space within the die substrate.